1. Field of the Invention
The present invention relates to a rotating electrical machine with a homopolar structure including a stator and a rotor rotating around a same axis of rotation as the stator, housed in a frame, at least the stator or the rotor consisting of at least one electrical coil of an annular shape borne by a magnetic annular frame yoke including at least two angularly shifted poles at an equal distance from each other, these poles being formed by tabs firmly attached to said annular frame yoke and folded parallel to said axis.
2. Description of the Related Art
The structure and the operation of an electric machine of this type, such as an electric rotating machine, are described in patents FR 00/06298 and BR 18083/FR (inventor Francois Bernot).
FIG. 1 shows the state of the prior art for this homopolar structure, in an octopolar version, with a three-phase stator with claws and a rotor with surface magnets. Another version may include a rotor with embedded magnets.
Another version may include a polyphase stator, the number of phases being arbitrary (greater than or equal to one), another version may include an inverted external rotor.
The embodiment of FIG. 1 includes three identical stators, which will be noted in this document as phases when they are complete with their coil (c4, c5 or c6). Said stators are numbered as (c1), (c2) and (c3). These wafers are phase-shifted relatively to each other by a mechanical angle of about 30°. In the case of the embodiment shown in FIG. 1, the angle (c10) substantially has a value of 30° and the angle (c11) substantially has a value of 60°. The angle (c10) substantially corresponds to the third of the electric angle of the rotating machine, said electrical angle being equal to 360° (one turn) divided by the number of pairs of poles (four in this octopolar case). The angle (c11) substantially has a value of twice the angle (c10). These angular shifts may be different, depending on the applications, but these variations fall under the known state of the prior art, notably applied to other structures of rotating machines They are only used for optimizing the final machine A two-phase version of said machine will only include two stators (c1) and (c2) which would then be shifted by an angle (c10)=45° in the octopolar embodiment described in FIG. 1. The rules for calculating the angular shifts between phases or respective stators are part of the state of the prior art.
In the embodiment of FIG. 1, the stators (c1), (c2) and (c3) have a structure with claws, which is characterized by apparent undulation of stator coils, noted as (c4), (c5) and (c6), respectively around planes of rotation X/Y (c12) of each stator. Said undulation may be obtained by twisting the stator teeth, as proposed by patent BR 18075/FR, or further by encircling the coils, (c4), (c5) and (c6) as proposed by patent BR 18083/FR.
In the latter clever embodiment, shown in FIG. 2, for a number of poles equal to 28, the stators (c1), (c2) and (c3) are all made in the same way, from two identical wafers (b1) and (b2), clamping a coil (b3). Said wafers are assembled onto each other, according to patent BR 18083/FR, so that their respective teeth (b4) and (b5), are substantially equidistant. The wafer (b1) is laid on the wafer (b2), as indicated by the arrow (b7). The contact areas (b30) between the wafers (b1) and (b2) have to be made properly, in order to avoid undesirable magnetic gaps in the contact area.
The shape of this contact area (b30) may not consist of a coplanar plane along X/Y (c12), but may adopt any other shape such as an undulation or further a crenellation, which would allow relative angular setting of said wafers (b1) and (b2). The wafer (b2) is angularly shifted relatively to the wafer (b1). Said setting angle (b6) in the case of the stator of FIG. 2 has substantially the value of half the electric angle of the machine, i.e. for this polarity of 14 pairs of poles shown in FIG. 2, the value: 12,857°.
It is important to note that the embodiments of FIGS. 1 and 2 consider that each tooth (b4) and (b5) forms a complete electric pole of the machine Therefore, in FIG. 1, we are in the presence of an assembly of single-phase electric rotating machines, axially gathered around a same rotor (c7). Said rotor may be of several natures, synchronous, asynchronous or with variable reluctance. The different embodiments known to this day of the rotors are part of the state of the prior art, they are all adapted to the presence of an assembly of stators with claws, as described in FIG. 1.
We shall designate subsequently in this document, the stators (c1), (c2) and (c3) as <<phases>>, in order to clarify their role; the rotor is common to the three phases. In the whole following description, we shall therefore consider the assembly formed by two wafers (b1) and (b2), clamping a coil (b3) as a complete phase. FIG. 3 again assumes in a more synthetic way this proposal, by showing both of these wafers (d1) for (b1), and (d2) for (b2), which are gathered against each other along the direction (d3), in order to form a single phase (d4), as described above corresponding to the joining of two wafers (b1) and (b2), clamping a coil (b3). A note should be made at this stage of the description of the state of the art, of the benefit of providing a means for axially maintaining the wafers (b1) and (b2) on each other, which may for example consist in an elastic clamping washer, mounted in any location of the axis of rotation of the plane XY (c12).
All these descriptions of FIGS. 1 and 2 are part of the state of the prior art. They include the version with an inverted stator, wherein the teeth (b4) and (b5) of the wafers (b1) and (b2) are located on the outer periphery, with a rotor which is located exteriorly to the stator.
The state of the prior art clearly shows the interchangeability of the different elements of an electric rotating machine, notably their internal or external relative positions, as shown in FIG. 4. The phase (d4), consisting of two wafers (d1) and (d2), may be located on the outside of a part (e2), in order to then form a single-phase homopolar rotating machine (e4). The phase (d4), consisting of two wafers (d1) and (d2) may be located inside a part (e3), in order to then form a single-phase homopolar rotating machine (e5). Axial juxtaposition of these complete machines (e4) or (e5), angularly shifted by an adequate angle, as known from the state of the art explained above, forms a polyphase rotating machine.
In this presentation of FIG. 4, the parts (d4), (e2) and (e3) may be static or rotary. If a part (d4) is rotary, it has to be powered either by rings or by any other system (rotating diodes for example).
The stator combination (d4) and with rotating magnets (or wound inductor) (e2) corresponds to a machine (e4) forming a so-called synchronous machine.
The phase (d4) is then powered with alternating current and according to so-called brushless control methods known to one skilled in the art.
The stator (d4) combination and with rotating magnets (or wound inductor) (e3) corresponds to a machine (e5) forming a so-called inverted synchronous machine. The phase (d4) is then powered with alternating current and according to the known so-called brushless control methods.
The stator (e3) and rotor (d4) combination, corresponds to a machine (e5) forming an alternator with claws, a so-called Lundell alternator, widely used in heat engines.
All the other combinations are possible, such as a rotor (d4) and stator (e2) configuration or further a rotor (d4) and stator (e3) combination, or else both rotating portions (d4) and (e2), or further both rotating portions (d4) and (e3).
These different combinations are widely described in the state of the art, for rotating machines with a coplanar structure.
Publication No. EP 1 263 115 A2 of the European Patent application No. 02253728, as well as publication No. EP 1 770 846 A2 of the European Patent application No. 06020595 both describe annular phase wafers, provided with teeth, the tooth leg of which has constant radial thickness (i.e. along the radius of the wafer).